Pat dry baby scallops and lay in an even layer on a plate. Season with salt and pepper and set aside.

Melt butter in a small saucepan over medium heat. Continue to heat butter until it turns golden brown and smells nutty, about 4 minutes. Remove from heat and let cool slightly.

Combine water, fish sauce, sugar, lime juice, and rice vinegar in a medium bowl, stirring until sugar is dissolved. Add brown butter, stirring until combined. Set aside.

Combine mayonnaise with sambal and sesame seeds, mixing until combined. Set aside.

Melt 1 tablespoon oil in a large saute pan over medium- heat. Add scallops, making not to overcrowd the pan, and cook until firm and golden brown, about 3-4 minutes. Reduce heat to low and add brown butter nuoc cham, stirring to combine. Simmer for 1 minute and remove from heat.

Arrange sandwiches. Spread sambal aioli on toasted rolls and arrange sliced cucumber on one side. Fill with scallops and top with chopped peach, pickled fresnos, fresh cilantro, and basil. Serve with lime wedges if desired.